US4208449A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making an electric resistor having a resistance body consisting of silicon carbide having a negative temperature coefficient
Assignee: US Philips Corp
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Filing: 1978-02-23
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Granted: 1980-06-17
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Expires: 1998-02-23
Abstract
Abstract A method of making an electric resistor having a negative temperature coefficient of resistance whose resistance body consists of p-type doped pyrolytic polycrystalline cubic silicon carbide.
Inventors
- 👤 Wilhelmus F. Knippenberg
- 👤 Gerrit Verspui
- 👤 Siegfried H. Hagen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:49
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/04; H01C7/042; H01C7/048; Y; Y10; Y10S; Y10S438/00; Y10S438/931
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
103 words
A method of manufacturing a resistance body for an electric resistor, said resistance body consisting of p-type doped pyrolytic polycrystalline cubic silicon carbide, said method consisting essentially of passing a mixture of a gaseous silicon compound, a gaseous carbon compound or a gaseous silicon carbon compound and a gaseous compound of a doping element, said doping element being only a p-type doping element, along a support heated to the pyrolysis temperatures of said gaseous compounds to thereby cause pyrolysis of said gaseous compounds and cause deposition on said support only of a compact coating of p-doped polycrystalline cubic silicon carbide on said support.
Claim 2
Independent Claim
103 words
A method of manufacturing a resistance body for an electric resistor, said resistance body consisting of p-type doped pyrolytic polycrystalline cubic silicon carbide, said method consisting essentially of passing a mixture of a gaseous silicon compound, a gaseous carbon compound or a gaseous silicon carbon compound and a gaseous compound of a doping element, said doping element being only a p-type doping element, along a support heated to the pyrolysis temperatures of said gaseous compounds to thereby cause pyrolysis of said gaseous compounds and cause deposition on said support only of a compact coating of p-doped polycrystalline cubic silicon carbide on said support.
Claim 3
Dependent Claim
20 words
A method as claimed in claim 1, characterized in that a conducting or non-conducting wire or tape-shaped support is used.
Claim 4
Dependent Claim
30 words
A method as claimed in claim 2, characterized in that a wire consisting of an element of the group consisting of tungsten, carbon and molybdenum is used as a support.
Claim 5
Dependent Claim
23 words
A method as claimed in claim 3, characterized in that a compound of boron is used as a compound of a doping element.
Claim 6
Dependent Claim
23 words
A method as claimed in claim 3, characterized in that a compound of aluminum is used as a compound of a doping element.
Claim 7
Dependent Claim
49 words
A method as claimed in claim 4, characterized in that the compound of boron at a pyrolysis temperature between about 1200° and about 1350° C. is used in a concentration in the range between 5.10 -3 % by volume and 7.10 -1 % by volume of the pyrolysis gas.
Claim 8
Dependent Claim
51 words
A method as claimed in claim 4 characterized in that the compound of boron at a pyrolysis temperature between about 1350° C. and about 1500° C. is used in a concentration in the range between 2 10 -3 % by volume to 5.10 -2 % by volume of the pyrolysis gas.
Claim 9
Dependent Claim
46 words
A method as claimed in claim 5, characterized in that the compound of aluminum at a pyrolysis temperature of between about 1200° and 1500° C. is used in a concentration in the range between 0.003% by volume and 0 0.03% by volume of the pyrolysis gas.
References Cited (Backward Citations)
US3157541A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-06-17 | 1983-12-17 | 1984-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-06-17 | 1987-12-17 | 1988-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-06-17 | 1991-12-17 | 1992-06-17 | $7700.00 | Window Closed / Lapsed |